Acoustic analyses and perception experiments were conducted to determine the effects of brief deprivation of auditory feedback on fricatives produced by cochlear implant users. The words /si/ and /ʃi/ were recorded by four children and four adults with their cochlear implantspeech processor turned on or off. In the processor-off condition, word durations increased significantly for a majority of talkers. These increases were greater for children compared to adults, suggesting that children may rely on auditory feedback to a greater extent than adults. Significant differences in spectral measures of /ʃ/ were found between processor-on and processor-off conditions for two of the four children and for one of the four adults. These talkers also demonstrated a larger /s/-/ʃ/ contrast in centroid values compared to the other talkers within their respective groups. This finding may indicate that talkers who produce fine spectral distinctions are able to perceive these distinctions through their implants and to use this feedback to fine tune their speech. Two listening experiments provided evidence that some of the acoustic changes were perceptible to normal-hearing listeners. Taken together, these experiments indicate that for certain cochlear-implant users the brief absence of auditory feedback may lead to perceptible modifications in fricative consonants.

The fundamental frequencies of daily life utterances of Japanese infants and their parents from the infant’s birth until about of age were longitudinally analyzed. The analysis revealed that an infant’s mean decreases as a function of month of age. It also showed that within- and between-utterance variability in infant is different before and after the onset of two-word utterances, probably reflecting the difference between linguistic and nonlinguistic utterances. Parents’ mean is high in infant-directed speech (IDS) before the onset of two-word utterances, but it gradually decreases and reaches almost the same value as in adult-directed speech after the onset of two-word utterances. The between-utterance variability of parents’ in IDS is large before the onset of two-word utterances and it subsequently becomes smaller. It is suggested that these changes of parents’ are closely related to the feasibility of communication between infants and parents.

In seeking an acoustic description of overloaded voice, simulated environmental noise was used to elicit loud speech. A total of 23 adults, 12 females and 11 males, read six passages of duration, over realistic noise presented over loudspeakers. The noise was canceled out, exposing the speech signal to analysis. Spectrum balance (SB) was defined as the level of the band relative to the band. SB averaged across many similar vowel segments became less negative with increasing sound pressure level (SPL), as described in the literature, but only at moderate SPL. At high SPL, SB exhibited a personal “saturation” point, above which the high-band level no longer increased faster than the overall SPL, or even stopped increasing altogether, on average at for females and for males. Saturation occurred below the personal maximum SPL, regardless of gender. The loudest productions were often characterized by a relative increase in low-frequency energy, apparently in a sharpened first formant. This suggests a change of vocal strategy when the high spectrum can rise no further. The progression of SB with SPL was characteristically different for individual subjects.

An application of functional data analysis (FDA) (Ramsay and Silverman, 2005, Functional Data Analysis, 2nd ed. (Springer-Verlag, New York)) for linguistic experimentation is explored. The functional time-registration method provided by FDA is shown to offer novel advantages in the investigation of articulatory timing. Traditionally, articulatory studies examining the effects of linguistic variables such as prosody on articulatory timing have relied on comparing the durations of speech intervals of interest defined by kinematic landmarks. Such measurements, however, do not preserve information on the detailed, continuous pattern of articulatory timing that unfolds during these intervals. We present an approach that allows the analysis of entire, continuous kinematic trajectories obtained in a movement tracking experiment examining the influence of a phrasal boundary on articulatory patterning. FDA time deformation functions, after alignment of test and reference (control) signals, reveal delaying of articulator movement (i.e., slowing of the internal clock rate) in the presence of a phrase boundary as the speech stream recedes from the boundary. This is a theoretically predicted pattern (Byrd and Saltzman, 2003, The elastic phrase: Modeling the dynamics of boundary-adjacent lengthening, Journal of Phonetics31, 149–180.), which would be more difficult to validate with a traditional interval-based approach. It is concluded that the FDA time alignment method provides a useful tool for characterizing timing patterns in linguistic experimentation based on continuous kinematic trajectories.

Interaction of Korean and English stop systems in Korean-English bilinguals as a function of age of acquisition (AOA) of English was investigated. It was hypothesized that early bilinguals (mean ) would more likely be native-like in production of English and Korean stops and maintain greater independence between Korean and English stop systems than late bilinguals (mean ). Production of Korean and English stops was analyzed in terms of three acoustic-phonetic properties: voice-onset time, amplitude difference between the first two harmonics, and fundamental frequency. Late bilinguals were different from English monolinguals for English voiceless and voiced stops in all three properties. As for Korean stops, late bilinguals were different from Korean monolinguals for fortis stops in voice-onset time. Early bilinguals were not different from the monolinguals of either language. Considering the independence of the two stop systems, late bilinguals seem to have merged English voiceless and Korean aspirated stops and produced English voiced stops with similarities to both Korean fortis and lenis stops, whereas early bilinguals produced five distinct stop types. Thus, the early bilinguals seem to have two independent stop systems, whereas the late bilinguals likely have a merged Korean-English system.

Perception of second language speech sounds is influenced by one’s first language. For example, speakers of American English have difficulty perceiving dental versus retroflex stop consonants in Hindi although English has both dental and retroflex allophones of alveolar stops. Japanese, unlike English, has a contrast similar to Hindi, specifically, the Japanese /d/ versus the flapped /r/ which is sometimes produced as a retroflex. This study compared American and Japanese speakers' identification of the Hindi contrast in CV syllable contexts where C varied in voicing and aspiration. The study then evaluated the participants’ increase in identifying the distinction after training with a computer-interactive program. Training sessions progressively increased in difficulty by decreasing the extent of vowel truncation in stimuli and by adding new speakers. Although all participants improved significantly, Japanese participants were more accurate than Americans in distinguishing the contrast on pretest, during training, and on posttest. Transfer was observed to three new consonantal contexts, a new vowel context, and a new speaker’s productions. Some abstract aspect of the contrast was apparently learned during training. It is suggested that allophonic experience with dental and retroflex stops may be detrimental to perception of the new contrast.